I hope I will help you. ET depends on weather, factors of crop and crop management and environmental conditions. If you have the same conditions, only you changed the density of plants, the maximum ET will be in your system SRI, because your system have less coverage in the beginning.
I also agree with others. Sthe SRI planting will have higer ET at the beginning compared to the conventional planting due to higher evaporation. If the variety used in the SRI case will have more tillering and covering the ground quickly, the transpiration part could be more that the evaporation.